CHEMISTRY · Single correct · A Level · Chemistry · Kinetics · Kinetics
Problem
During the reaction 2 NO₂(g) + F₂(g) → 2 NO₂F(g), trace amounts of NO(g) dramatically increase the rate. A proposed mechanism is shown below.
(1) NO + F₂ → NOF + F (slow)
(2) F + NO₂ → NO₂F (fast)
(3) NOF + NO₂ → NO₂F + NO (fast)
Which observation would most strongly support that NO is acting as a true catalyst in this reaction?
(a) Increasing the initial concentration of NO changes the equilibrium constant for the overall reaction.
(b) The net concentration of NO remains unchanged because it is consumed in one elementary step and regenerated in a later step.
(c) Adding a small amount of NO lowers the activation energy of only the fast steps, leaving the slow step unaffected.
(d) The reaction rate is unaffected by the concentration of NO once a minimal amount has been added.